delete-in-with.js

Google浏览器V8内核代码

// Copyright 2008 the V8 project authors. All rights reserved.
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// It should be possible to delete properties of 'with' context
// objects from within 'with' statements.
(function(){
  var tmp = { x: 12 };
  with (tmp) { assertTrue(delete x); }  
  assertFalse("x" in tmp);
})();